High‐Resolution Ion Mobility Spectrometry–Mass Spectrometry on Poly(methyl methacrylate)

Abstract

Synthetic polymers are produced in industry to serve a global market across a wide range of areas.[1a-c] Increasingly complex polymeric structures have been developed to provide desirable properties and functions.[1d] The performance of these products depends on many factors such as endgroup composition, molecular weight distribution (MWD), and 3D conformation.[1e,f] Various analytical methods have been developed to obtain information about these properties. Conventional analytical techniques to study polymer systems include gel-permeation chromatography (GPC), [2a] Fourier-transform IR (FTIR), [2b] NMR spectroscopy, [2c] and differential scanning calorimetry (DSC).[2d]The development of "soft" ionization methods such as elecrospray ionization (ESI) [3a,b] and matrix-assisted laser desorption/ionization (MALDI) [3c,d] allowed mass spectrometry (MS) to become one of the most promising analytical methods for the analysis of polymeric systems. MS has the ability to characterize a dispersed polymer containing oligomers with different structures such as isomers or isobaric molecular weights. The combination of liquid chromatography (LC) and MS reduces the effects of ion suppression that may occur in an infusion MS analysis and provides an extra dimension of separation.[4] However, a relatively long separation time (> 30 min for HPLC, around 10 min for UPLC) is needed and a complex elution system using a variety of solvents has to be developed to suit a specific polymeric system.The combination of ion mobility spectrometry (IMS) and ESI-MS has been developed to analyze biomolecules and biopolymers.[5] Ion mobility describes how fast an ion in the gas phase moves through a drift cell that is filled with a carrier buffer gas under the influence of an electric field. More compact ions with a smaller collision cross-section will drift more quickly than expanded ions. The time-scale for separations in IMS is 100 ms to 10 ms, which is ideally suited for interfacing with an MS instrument. The extra dimension of separation based on drift time (t D ) provided by IMS is also highly complementary to the information obtained by MS. Although some studies on IMS-MS measurements of blends of disperse macromolecules, for example, poly(ethylene glycol) (PEG), have been reported, studies using IMS-MS on complex synthetic polymer systems are still limited. [6] Here, we demonstrate the power of using high resolution IMS-MS to study a poly(methyl methacrylate) (PMMA) synthesized by radical polymerization using peroxide initiator (tert-butyl peroxy-3,5,5-trimethylhexanoate) in solvent. Comprehensive studies on acrylic polymer produced by radical polymerization using MS have been done in the past decade. [7] It has been proven that high-resolution MS can discriminate between the effects of various polymerization mechanisms such as b-scission, chain transfer to solvent, radical transfer to solvent from the initiator, etc.[7] A system with complex endgroup combinations is expected since various initiation and termination reactions may ...

Collision-Induced Dissociation Ion Mobility Mass Spectrometry for the Elucidation of Unknown Structures in Strained Polycyclic Aromatic Hydrocarbon Macrocycles

“…Whereas MS was the main method to detect the side products, it does not provide information on the molecular shape. Ion mobility spectrometry, as a post-ionization separation method, can separate ions with various sizes, shapes, and conformations according to their collision cross-section (CCS), thus representing a complementary method that could also distinguish isomers with the same m / z but different structures. , Ion mobility mass spectrometry (IMMS) has already been used for the structure and architecture analysis of polymers, − metallosupramoleculars, − and biomolecules. − Hoskins et al distinguished the linear and cyclic poly­(ε-caprolactone) according to their drift time differences in varied charge states by IMMS. Li et al used IMMS to separate and characterize a series of synthesized linear and cyclic metallosupramoleculars with varied oligomeric numbers.…”

Synthesis of high-molecular-weight aliphatic polycarbonates by organo-catalysis

“…The different series can be separated by Ion Mobility Separation (IMS). 35 The separated spectra of up to tetraly charged polymers are shown in Fig. 4b.…”

Synthesis of Amphiphilic Block Copolymers Based on SKA by RAFT Polymerization

“…A conclusive analysis of the series of original ESI measurement without the separation of charge states is quite complicated. Therefore, the coupling of the ESI with IMS is adaptable to simplify the mass spectrum (Figure b) . At the same time we also have to take into account by applying IMS that the signal might change during the measurement.…”

“…However, compared to ESI‐mass spectrometry (MS) MALDI‐MS is a relative harsh technique as some polymers are not kept intact and can fragment during laser exposure. The coupling of ion mobility separation (IMS) and ESI‐MS has been developed to introduce an additional separation dimension and is frequently used to analyze biomolecules and biopolymers . The separation time in IMS vary from 100 µs to 100 ms, which matches for interfacing with an MS instrument.…”